Tris(2-hydroxyphenyl)methanes and various derivatives thereof are known in principle.
G. Casiraghi, G. Casnati and M. Cornia, Tetrahedron Letters, No. 9, 679-682 (1973) describe the synthesis of mono- or dialkylated tris(2-hydroxyphenyl)methanes by reacting corresponding phenols with triethyl orthoformates.
M. B. Dinger and M. J. Scott describe in Chem. Commun., 1999, 2525/2526, Inorg. Chem. 2000, 39, 1238-1254 and Inorg. Chem. 2001, 40, 1029-1036 the synthesis of various tris(3,5-dialkyl-2-hydroxyphenyl)methanes, where methyl, t-butyl and t-pentyl radicals are described as alkyl radicals. The trishydroxy compounds are used as complexing agents for zinc and alkali metal ions.
M. B. Dinger and M. J. Scott, Eur J. Org. Chem. 2000, 2467-2478 furthermore describe the further reaction of the OH group of tris(3,5-dialkyl-2-hydroxyphenyl)-methanes. The OH functions can be derivatized through reaction with halogencarboxylic acid esters and hydrolysis and/or further reactions. Dinger and Scott describe, for example, tris(3,5-di-t-butyl-2-carboxymethoxyphenyl)methane, tris(3,5-di-tert-butyl-2-[(dimethylamido)methoxy]phenyl)methane, tris{3,5-di-tert-butyl-2-[N-(methylglycyl)carbonylmethoxy]phenyl}methane and tris(3,5-di-tert-butyl-2-[(benzylaminocarbonyl)methoxy]phenyl)methane. The derivatives can be used in each case as complexing agent, for example for Zn(II) ions.
K. Matloka, A. Gelis, M. Regalbuto, G. Vandegift and M. J. Scott, Dalton Trans., 2005, 3719-3721 or Separation Science and Technology, 41, 2006, 2129-2146 and M. W. Peters, E. J. Werner and M. J. Scott, Inorg. Chem., 2002, 41, 1701-1716 disclose functionalized tris(3,5-dialkyl-2-hydroxyphenyl)methanes, and specifically tripodal diglycolamides and their use for the complexing and separation of lanthanides. Tris(3,5-dialkyl-2-hydroxyphenyl)methanes in which the OH group is etherified with ω-amino or cyanoalkyl groups are used as intermediate of the synthesis.
R. Mitra, M. W. Peters and M. Scott, Dalton Trans., 2007, 3924-3935, further describe tris(2-hydroxyphenyl)methane derivatives which have terminal 2-pyridylmethyl-piperazine groups. These molecules can bind zinc ions and are used as catalysts for the phosphate diester synthesis. Tris[2-(2-hydroxyethoxy)-3-methyl-5-t-butylphenyl]-methane is disclosed as intermediate of the multistage synthesis.
EP 597 806 A1 discloses cyclohexyl group-containing glydidyl ethers for use as reactive thinners, flexibilizers or adhesion improvers. Various tris(2-hydroxyphenyl)methanes are described as intermediate of the synthesis, including those in which the OH function is etherified with a (substituted) 2-hydroxyethyl group.
US 2009/0155714 A1 discloses compositions for producing photoresists. Various tris(2-hydroxyphenyl)methane derivatives in which the OH function is esterified in each case with various carboxylic acids are used as a component for this.
It is known that surfactants aggregate to give micelles above the critical micelle concentration (cmc). The shape of these water-soluble aggregates depends on the structure of the surfactants and also on external parameters such as temperature or electrolyte concentration. Typically, spherical or rod-shaped micelles can form above the micelle concentration.
Under certain structural conditions and/or external parameters, long thread-like or worm-like micelles or associates can also form. Even at a relatively low surfactant concentration, this can lead to looping and overlapping of these long aggregates, as a result of which the viscosity of the surfactant solution increases significantly. A certain minimum stability of the micelles over time is prerequisite here. This temporarily formed network of surfactant micelles reacts, from a rheological point of view, either viscously or elastically, for which reason the term viscoelastic surfactant solutions is generally used. Micelles liberate individual surfactants, incorporate surfactants into the micelle association, disintegrate and reform again. Surfactant micelles which form viscoelastic networks are very stable over time before they disintegrate into individual segments and reform again, meaning that the micellar network can offer resistance to shearing of the surfactant solution and thereby reacts either viscously or else elastically. Further details relating to viscoelastic surfactants forming worm-like micelles such as hexadecyltrimethylammonium p-toluenesulfonate or cetylpyridinium salicylate are described, for example, in H. Hoffmann et al., Adv. Colloid Interface Sci. 1982, 17, 275-298 or M. R. Rojas et al., Journal of Colloid and Interface Science 342 (2010) 103-109).
On account of the properties discussed, viscoelastic surfactants are very particularly suitable as thickeners and can be used in various areas of technology.
US 2005/0155762 discloses betaines with alkyl chains having 14 to 24 carbon atoms, for example oleylamidopropylbetaine or erucylamidopropylbetaine as viscoelastic surfactants with a thickening effect.
U.S. Pat. No. 7,461,694 B2 discloses zwitterionic surfactants with alkyl chains of from 16 to 24 carbon atoms as viscoelastic surfactants.
WO 2008/100436 A1 discloses a viscoelastic surfactant mixture of cationic, anionic or zwitterionic surfactants and a polymer. The surfactants have alkyl chain lengths of from 12 to 25 carbon atoms.
In the cited disclosures, surfactants with long alkyl chains are used in each case for the formation of viscoelastic surfactant solutions. One disadvantage of viscoelastic surfactants with long alkyl chains is that, upon contact with nonpolar liquids, they solubilize these, as a result of which the worm-like micelles are converted to spherical aggregates and the viscoelasticity is lost. Moreover, in contact with other surfactants, these viscoelastic surfactants generally form mixed micelles, as a result of which the viscoelasticity can likewise be lost. Structures with short alkyl chains or structures which deviate from the customary linear structure principle of the surfactants as a rule form spherical micelles or only short anisometric aggregates and thus no viscoelastic surfactant solutions.
The best known viscoelastic surfactants are cationic surfactants such as hexadecyltrimethylammonium p-toluenesulfonate or cetylpyridinium salicylate. Cationic surfactants with long alkyl radicals are ecotoxicologically very acceptable (see e.g. Versteeg et al. Chemosphere 24 (1992) 641)). Since they adsorb particularly well on surfaces on account of their positive charge, they moreover lose some of their effect in the case of some applications. There is therefore a need for surfactants with a more favorable ecotoxicological profile and lower adsorption tendency.